System of motor control



Patented Sept. 27, 1921.

2 SHEETSSHEET 1.

@WQ Q H. L. VAN VALKENBURG.

SYSTEM OF MOTOR CONTROL.

APPLICATION FILED APR. 14, 1920. 1,391,808.

2 SHEETS-SHEET 2.

Patented Sept. 27, 1921.

position.

UNITED sra'nzsv PATENT oFF'ics.

HERMON L. VAN VALKENZBURG, or MILWAUKEE, W sconsin, Assrenon TO mous- TRIAL'CONTROLLEB. COMPANY, or MILWAUKEE, WISCONSIN, A CORPORATION or WISCONSIN.

SYSTEM OF MOTOR CONTROL.

Specification of Letters Patent. Patented Sept, 27, 1921,

Originalapplication filed July 25, 1918, Serial No. 246,635. Divided andthis application filed April 14,

1920. Serial No. 373,771.

To all whom it on conaem:

Be it known that HERMON L. VAN VAL- KENBURG, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented a certain new and useful'Improvement in Systems of Motor Control, of which the following is a specification.

My invention relates to systems of motor control, especially. those in which a compensator is employed. The object of the invention is to provide a system by which the motor may first be supplied through the auto transformer of the compensator then supplied directly from the line, and the auto transformer cut out of circuit. In the particular embodiment shown in the accompanying drawings the compensator is hand operated and constructed in the same manner as shown in my copending application, Se-

rial No. 246,635 filed July 25, 1918, ofwhichmy presentapplication is a division.

To briefly describe the illustrated mechanism which is in the present case embodied in the system, there is a starting switch adapted to connect the motor through the auto transformer and a running switch.

adapted to connect the motor directly to the line. An operating handle is provided which normally occupies an ofi' position but can be swung forward and backward to manipulate the switches. When the handle is moved forward from off position it closes the starting switch and a detent automatically takes hold and maintains the starting switch in closed position. If the operator permits the handle to v return all the we back to off position, the detent is automatically tripped and the parts returned to normal pre starting posit1on',lbut if he permits the handle to comeonly part way back, as he should do if he intends to start the motor, the mechanism picks up the running switchso that a second forward movement of the handle closes the running switch and finally permits a second detent to take hold and maintain the running switch in closed handle to move back to the original off position during the course of which movement the first detent is automatically tripped, thus permitting the starting switch to open. The second detent, which is shown in-the form The operator then permits the of a low voltage release, holds the running Fig. 3 is a side elevation of a portion of the casing in which the mechanism is usually inclosed, this view showing the indicator for advising the attendant as to the condition of the apparatusthat is, whether the mechanism is on or off.

Like numerals denote like parts throughout the several views.

Referring first to the physical part or operating mechanism which forms a component part of the system, a rock shaft 8 is journaled in the casing 9 and provided with an operating handle 10. A spring 11, shown in Fig. 3, constantly urges the handle toward initial position, as shown in Figs. 2 and 3.. One end of the spring overlies the handle while the other end engages the lug 12 fastened on the outer side of the casing.

' andrunning switches respectively. The rear bar 18 carries stationary contacts 38 and 39 of the auxiliary switches. 1 Rigidly fastened to a rock shaft 25 are starting switch arms '26 provided at their ends with contacts 27 which engage the contacts 20. Similarly, a

rock shaft 80 has rigidly fastened to it T1111- ning switch arms 31, provided at their ends with contacts 32 which engage the contacts 21. Shaft 30 also has rigidly fastened to it the auxiliary switch arms 34, 35 provided at 60 i neoted to an arm 74 rigidly fastened to rock their ends with contacts 36, 37 adapted to engage the stationary contacts 38, 39, fastened to bar 18. The parts are so arranged that when the arms of the running switch are in closed position, the arms of the auxillary switch are in open position, and vice versa.

Shaft 25 is operated by a plate 40 which is fastened to it. A spring 41 is fastened at one end of said plate and at the other end to a stationary rod 42. This spring tends to keepl the starting switch open. The closure of t a link 44 adapted to en age a pin 45 projecting from the side of p ate 40. Said link is actuated by an arm 47 rigidly fastened to rock shaft 8. The link and the arm are articulately connected by a pin 46 which also performs the function of a trip as hereinafter explainedf Link 44 is longitudinally slotted to permit the operating handle to be rotated part way back to initial position while the starting switch remains closed.

An arm 48 on the plate 40 serves to limit the movement of shaft 25 and arms 26 under the influence of spring 41. When the starting switch has reached closed position it is held there by a detent 50 which is pivoted .at one end upon the projection 51on the plate 16. A spring 52 urges the free end of the detent upward. Said detent has a slot 53, at one end of which a shoulder 54 is formed. When the pin 45 moves forward and reaches the shoulder 54, the spring 52 causes-the shoulder to engage the pin and hold the starting switch closed. The detent has a tail 55 in position to be engaged by pin 46 about the time the operating handle 10 returns to initial position, consequently as the handle reaches initial position on backward movement, the pin 46 engages tail 55 and causes detent 50 to release pin 45, thus permitting spring 41 to rotate shaft 25 and swing the starting switch arms 26 to open position.

The shaft 30, which operates the running switch arms 31 and auxiliaryswitch arms 34 and 35 is operated by a plate '60 which is constantly urged by a spring 61 in a direc tion to open'the switch. The lower'end of the spring is attached to rod 42. An arm 64-is formed on plate 60 in position to strike the stationary bar 18 and limit the amount of rotation of shaft 30 under the influence of spring 61. The closure of the running switch is effected by means of a connector link 68, having a shoulder 69 adapted to engage a pin 70 projecting from the side of the arm 71 which forms a part of the plate 60. Said connector link is articulately conshaft 8. The parts are so arranged that when the operating handle 10 is rotated sufiicientl forward, the shoulder 69 will engage the pm 70 and close the running switch proe starting switch is effected by means of hooked detent in acting position are electrovided the holdout mechanism permits the connector link to act. This hold out mechanism consists of a pin 76 which underlies a cam 77 formed on the under side of the link. Pin 76 is carried by the plate 40 fastened to the starting switch, and the design is such that if the starting switch is closed, the pin 76 will be out of reach of cam 77, and hence the connector link will be able to enga e the pin 70 and close the running 75 switch; but if the starting switch is open, the pin 76 will occupy a position where the cam 77 will ride upon it and will cause the connector link in its forward movement to rise sufliciently to cause the shoulder 69 to clear the pin 70 and thus produce no effect upon it. It Will thus be seen that the connector 68 cannot close the running switch unless the starting switch is closed.

When the running switch reaches closed 5 position it is held there by a latch or detent 80, pivoted upon a stationary pin 81. Said detent is overbalanced so as to assume acting osition. It is provided with a hook, the ront edge whereof forms a cam located in' position to be engaged by the anti-friction roller 86 formed at one end of a link 87. Said link is pivotally supportedby the arm 71 of the plate 60 and has a spring 88 for urging its free end downward to engage the hook. As the link moves forward in the direction to close the running switch, it becomes engaged by the hook. The means which I have provided for holding this magnetic and consist in the present case of a winding 90 held in stationary position and adapted to attract the armature 91 fastened to the rear end of the detent. The parts are so constructed that unless the winding 90 is sufliciently energized, the tension of the spring 61 will be sufficient to disengage the link 87 from the detent and permit the spring 61 to open the running switch. The winding 90 and detent 80, therefore, form parts of a low voltage release.

Now referring to the diagram, Fig. 1, which shows the electric connections;

The generator 100 energizes the line conductors 101, 102 and 103. The arms 26 of'115 the starting switch move in unison to engage and disengage the stationary'contacts 20, individually. The line conductor 101 is connected to one of said stationary contacts by a conductor 110. The line conductor 102 is connected to another of said stationary contacts by conductor 111, and the line conductor 103 is connected to the third stationary contact through a conductor 112. The autotransformer 3 has two coils 120 and 121. These coils are V connected and their ends are connected to the starting switch arms by the respective conductors 125,126 and 127 The running switch arms 31 are adapted to engage the stationary contact 21 individ- 130 ually. The arms 34 and 35 of the auxiliary switch are adapted to engage respectively the contacts 38 and 39. Contact 38 is connected by a conductor 130 to an intermediate point on'the coil 121. Contact 39 is connected by conductor 131 to an intermedlate point on the coil 120. The motor 135 is connected to the three arms of the running switch by conductors 136, 137 and 138 respectively. The winding 90 is connected by a conductor 140 to the switch 35. The other end of the winding is connected by a conductor 141 to the contact 142 of the overload relay. A stationary contact 143 of this relay is connected to contact 142 ,by a normally closed switch 144, to which is attached a core 145, working in a coil 146, one end of which is connected by a conductor 148 to the line conductor 101. The other end of the coil is connected to one of the contacts 21. The apparatus is so designed that if-the current in the coil 146 exceeds a predetermined maximum the switch 144 will open and break the circuit through the winding 90, thus releasing the detent 80 and permitting the running switch to open. In a similar manner, two stationary. contacts 150 and 151 are bridged by a normally closed switch 152 having a core 153, working in a coil 154. One end of said coil is connected by conductor 112 to the line conductor 103 and the other end is connected to one of the contacts 21. Contacts 143 and 150 are connected together in the auxiliary circuit and hence this switch also will open if the current becomes too great. Contact 151 is connected by a conductor 158 to a push button switch 159 which connects it to a conductor 160 and thence tothe switch 34. By pushing this button, the auxiliary circuit may be opened, thus denergizing the winding 90 and pen mitting the running switch to open. Thus the auxiliary circuit may be opened (and consequently the running switch caused to be opened) either manually by opening the push button switch or automatically in case the electrical values in the auxiliary circuit go either above or below preordained limits.

From the foregoing it will be evident that the switches are necessarily operated in their proper sequence and that a certain amount of delay must occur between the closure of the starting switch and the closure of the running switch. The operator must first move the operating handle forward far' enough to completely close the starting switch, them move the handle backward to pick up the running switch and then'move the handle forward an appreciable distance before the running switch is closed.

. Attention is called to another divisional application for switch mountings filed on the 26th day of April, 1920, Serial No. 376,473.

Having thus described my invention what I claim as new and desire to secure by Letters Patent, is

1. An alternating current compensator having a starting switch and a running switch, both tending to open, an auto-transformer, a starting circuit including said transformer and starting switch, a running circuit including said running switch, a detent for holding the starting switch closed, a second detent for holding the running switch closed, and means for tripping the first detent and thereby permitting the starting switch to open when the operating handle approaches initial position during its backward movement.

2. A compensator having. a starting switch, and a running switch, both tending to open, a detent for holding the starting switch closed, a second detent for holding the running switch closed, an operating handle adapted when moved forward to close said switches, means operated by the handle for tripping the first detent, and means in circuit relation with the source of electromotive force for tripping the second detent when the voltage drops below a predetermined minimum.

3. A motor starter comprising a starting switch, a running switch, an operating handle adapted to close said switches in the sequence in which theyare mentioned as the handle'moves forward from initial position, a detent for holding the running switch in closed position independently of the operating handle, means controlled by said handle for opening the starting switch as the handle returns to initial position, and a low voltage release for releasing said detent and causing the running switch to open when the voltage in the supply circuit reaches a predetermined minimum.

4. A motor starter comprising a starting switch, a running switch, an operating han dle adapted to close said switches in the sequence in which they are mentioned, as the HERMON L. VAN VALKENBURG. 

